<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .sun {
      position: absolute;
      right: 200px;
      top: 50px;
      width: 150px;
      height: 150px;
      border-radius: 50%;
      background: #f8e353;
    }

    .sun::before {
      content: "";
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      width: 130px;
      height: 130px;
      border-radius: 50%;
      background: #ffd21f;
      filter: blur(10px);
      z-index: 1;
      animation: inlineSun 5s ease infinite;
    }

    .sun::after {
      content: "";
      position: absolute;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      width: 180px;
      height: 180px;
      border-radius: 50%;
      background: #fcf17c;
      z-index: -1;
      box-shadow: 0 0 40px #ffd21f;
      animation: sun 5s ease-in infinite;
    }

    @keyframes inlineSun {
      0% {
        opacity: 1;
      }

      50% {
        opacity: 0.5;
        width: 70px;
        height: 70px;
      }

      100% {
        opacity: 1;
      }
    }

    @keyframes sun {
      0% {
        box-shadow: 0 0 90px #ffd21f;
      }

      50% {
        box-shadow: 0 0 30px #ffd21f;
      }

      100% {
        box-shadow: 0 0 90px #ffd21f;
      }
    }
  </style>
</head>
<body>
  <!-- [css] 用css画一个太阳 -->
  <div class="sun"></div>

</body>


</html>